Consumer spending or consumer demand or consumption is also known as personal consumption expenditure. It is the largest part of aggregate demand or effective demand at the macroeconomic level. There are two variants of consumption in the aggregate demand model, including induced consumption and autonomous consumption.
A population is a summation of all the organisms of the same group or species, which live in a perticulargeographical area, and have the capability of interbreeding. In ecology, the population of a certain species in a certain area is estimated using the Lincoln Index.